Contents

The Machine

The machine I'm proposing we acquire is a router-based CNC table that my friend and I built.

The base of the actual CNC

The machine is a 4'x4' sized CNC table. It stands approximately 4' high from the ground, has a very sturdy steel frame, MDF slat table, extruded aluminum rails and v-bearing/steel angle bearings.
It has a Hitachi router which is attached to the Z axis holder with clamps and can route wood, foam, plastic, thick acrylic, etc.
The gantry, Y and Z axises are all driven by Acme screw drives, with DumpsterCNC anti-backlash nuts. They have NEMA24 motors with a HobbyCNC driver board] and power supply.
All wires are run through igus chain for the X and Y axis.

The bed is approximately 5'x5', and the cutting area is a bit smaller, approx. 4'x4'

A completed Joe's CNC (someone else's model)

The Good

This machine was bought as a kit (mostly) and was completely assembled. I worked with my friend to build it up and test it.
The machine moves, the drivers work, the software works, pretty much everything was working correctly the last time we had it powered up.
It comes complete.. Everything there. Power supply, driver, steppers, router, even a licenesed copy of Mach3.
It's very sturdy, and we didn't skimp out anywhere.. everything was done to the best we could.

The Challenge

The reason the machine isn't running now is twofold:

We had issues with the X gantry binding

The purpose my friend built it for became moot and he has not had a use for it since

The problems we had while trying to get it running is that the X steppers would stall out while attempting to move the gantry. I'm sure that this just requires either alignment, motor tuning, some combination of the two, or bigger motors. That was really the only issue we had with it. Unfortunately, shortly after we had this problem, he lost interest quickly (got into building kegerators and woodwoorking) and did not have the technical knowhow to get it running. He was busy with work and had no time to spend on getting it going. So there it has sat.

In theory all we should need is to tune up the motor controls (can be done through Mach3 and the driver board), and to get the gantrys moving properly. After that, we just need to mount the router and calibrate it, and then it can be up and running, and able to CNC things for us.
Worst case, we need to do some revamping on the screw drives, either with larger motors or using different supports. This shouldn't be too intensive, but it may require purchasing new parts.
We also may want to replace the V bearings with something better, such as pillow blocks at some point, but the v bearings are in use by many people and they should work for now.

The Price

He asked for $2000 for the whole thing. I have already put $500 towards it, so what's left is $1500. He spent over $4000 for the whole kit, so it's a good deal, considering other pre-made CNCs cost around $10k. I'm sure with our knowledge we can get this thing working for well under what we'd have to pay for a ready-made one.